Apparatus for showing the nature of combustion in internal combustion engines



April 4, 1939. G, D. BOERLAGE 2,153,114

APPARATUS FOR SHOWING THE NATURE OF COMBUSTION NT NNNNNNNNNNNNNNNNN GI Fi 11111 1111111 s5 I ll n CE

Patented Apr. 4, 1939 UNITED STATES PATENT OFFICE APPARATUS FOR SHOWING THE NATURE OF COMBUSTION IN INTERNAL COMBUSTION ENGINES Application September 16, 1935, Serial No. 40,752 In the Netherlands January 18, 1935 1 Claim.

The invention relates to the showing of the nature of the combustion in internal combustion engines, particularly to showing the occurrence of the so-called knocking or detonation. The detonation of a motor is attended with great, undesirable rises of pressure and temperature in the combustion space, such a rise of pressure generally causing vibrations which make them- 'selves heard as a metallic knock. Various methods have already been proposed to show the occurrence of this phenomenon, a known method being, for example, the one whereby a flexible diaphragm is fitted in the wall of the combustion space, which diaphragm suddenly sags when detonation occurs, thus causing the bouncing of a pin resting on the outside against the diaphragm. The application of the said method however, calls for a special construction of the cylinder so as to allow of the diaphragm being fitted at the proper place.

The object of the invention is to enable such a detonating combustion being shown readily in any given engine; this is achieved by detecting such vibrations of the outer wall of the cylinder as are caused by detonation. It has, in fact, been found that the occurrence of detonation as observed by the ear coincides with the occurrence of particularly strong vibrations of a special frequency range of cylinder walls and the parts connected therewith, for example, in the case of an air-cooled engine, cooling ribs, and even the crankcase. According to the invention use is made of a device fitted detachedly to the outside of the cylinder, which device in construction but not in function shows some resemblance to a hammer and anvil, which latter should be connected to the cylinder in such a manner that it forms a rigid whole with the cylinder. As a result vibrations are transmitted to the anvil, whilst the hammer is held on the anvil by the pressure of a spring. Apart from secondary phenomena the contact between hammer and anvil will be broken as soon as the force exerted by the spring becomes less than the product of the maximum acceleration of the anvil (and, therefore, of the hammer) resulting from the vibration and the mass of the hammer. Preferably electrical means will be used for showing the movement of the hammer with respect to the anvil.

The invention will now be set forth in more detail with reference to the drawing.

Fig. I shows somewhat schematically a cross section of a device according to the invention as designed for use with an air-cooled engine.

Fig. II is a partial cross sectional view showing alternate contact mechanism.

Referring to Fig. I numeral 1 is a section of a cooling rib of an engine cylinder. By means of a U-shaped bolt 3 passed through the hole 2, a saddle block 4 is fastened to the cooling rib in such a manner that it forms a rigid whole with it so that the vibrations of the rib will be transmitted to it. Onto this block serving as anvil, a cover 5 is screwed containing the ball 6 acting as hammer, this ball is attached to a fiat spring 1 fastened to one end of the cover and pressed against the anvil by this spring I. The spring extends beyond the ball and at a short distance above its free end lies the point of a contact screw 8 insulated from the cover. This screw 8 is connected to a pole of an electric battery of which the other pole is connected by means of a terminal screw 9 to the cover or any other part of the apparatus. An electric current indicator, e. g., a neon lamp, can be placed in the circuit. One possible circuit is shown in Fig. I. Instead of using an electric battery a dynamo, or electric generator could be used, while an electric bell could be substituted for a neon lamp. All such and other variations will be readily apparent to those skilled in the electrical art.

By means of the set screw 10 the pressure with which the ball is pressed against the anvil can be adjusted.

Referring to Fig. II wherein like parts are given the numerals of Fig. I, instead of arranging the mechanism so that the vibration causes an electrical circuit to close as in Fig. I, a contact member (H) extends to the underside of the spring (1) so that the vibration will cause an electric circuit to be broken.

Construction and adjustment of the apparatus are such that with normal non-detonating combustion the vibrations of cylinder and cooling rib are unable to lift the ball from the anvil. However, as soon as detonation occurs, the frequency and the intensity of the vibrations become such that the force exercised by the spring is insufficient to cause the ball to follow the rapid movement of the anvil, so that the contact between ball and anvil is broken and the end of the spring comes into contact with the contact screw 8, thus closing the circuit, causing an indication to be made, for example, the intermittent lighting of the glow lamp shown in Fig. I.

Numerous modifications of the various parts of the apparatus are possible. For instance, in the case of a water-cooled engine the manner in which the anvil is fastened to the cylinder is, of

detonative combustion in the cylinder of an aircooled internal combustion engine, a saddle shaped anvil fastened to a cooling fin on the outside wall of said cylinder, a hardened steel ball in contact with said anvil, a fiat spring attached at about its midpoint to said ball and holding the same in contact with said anvil, an insulated electrical contact post positioned near one end of said spring whereby vibratory contact with said electrical contact post will result from det- 10 onative combustion in said cylinder.

GERRIT DANIEL BOERLAGE. 

